1. Field of Invention
The present invention relates to slide rules for hyperalimentation or parenteral nutrition dosage computations.
2. Description of Prior Art
Hyperalimentation, also known as total parenteral nutrition, is a term defining the technique of intravenous therapy for providing nutrition to persons who are undergoing chemotherapy, which often causes these persons to reject normal nutrition, and to persons who, as a result of trauma, such as surgery, burns or shock, or other complications, are in a catabolic state of malnutrition. In prescribing dosages, it is useful for the physician to evaluate the effect of a particular dosage and component concentration on the patient. It is also useful for a pharmacist in labelling hyperalimentation solutions to known particular dosages and component concentrations.
Conventional general purpose slide rules, such as in U.S. Pat. No. 2,500,460, were not suitable for these purposes, since the indicia thereon were positioned according to logarithmic numerical relationships rather than according to the type of solutions being prescribed and administered. Other special purpose slide rules, such as in U.S. Pat. Nos. 1,488,823 and 3,814,308, were specially designed for performing calculations based on particular types of fluids and components and did not lend themselves to medical dosage computations. Finally, the slide rule disclosed in U.S. Pat. No. 3,747,847 gave estimated 24-hour therapy figures for intravenous therapy. However, this structure was based on which of eight particular physical conditions a patient might be in, and the patient's body weight. For these given conditions, the amounts of materials available in a single particular solution, on which the slide rule was based, was readily ascertained. However, for a particular patient and physical condition, the physician could not evalute the relative merits and effects of therapy using one of several alternative solutions for the patient, based on the components of the solutions, as well as the caloric content of the solutions.